The Electrostatic Production of High Voltage for Nuclear Investigations

Abstract

The developments in nuclear physics emphasize the need of a new technique adapted to deliver enormous energies in concentrated form in order to penetrate or disrupt atomic nuclei. This may be achieved by a generator of current at very high voltage. Economy, freedom from the inherent defects of an impulsive, alternating or rippling source and the logic of simplicity point to an electrostatic generator as a suitable tool for this technique. Any such generator needs a conducting terminal, its insulating support and a means for conveying electricity to the terminal. These needs are naturally met by a hollow metal sphere supported on an insulator and charged by a belt conveying electricity from earth potential and depositing it within the interior of the sphere. Four models of such a generator are described, three being successive developments of generators operating in air, and designed respectively for 80,000, 1,500,000 and 10,000,000 volts, and the fourth being an essentially similar generator operating in a highly evacuated tank. Methods are described for depositing electric charge on the belts either by external or by self-excitation. The upper limit to the attainable voltage is set by the breakdown strength of the insulating medium surrounding the sphere, and by its size. The upper limit to the current is set by the rate at which belt area enters the sphere, carrying a surface density of charge whose upper limit is that which causes a breakdown field in the surrounding medium, e.g., 30,000 volts per cm if the medium is air at atmospheric pressure. The voltage and the current each vary as the breakdown strength of the surrounding medium and the power output as its square. Also the voltage, current and power vary respectively as the 1st, 2nd and 3rd powers of the linear dimensions.